Power operated knife switch trigger locking means



H. KORSHAK April 23, 196s POWER OPERATED KNIFE SWITCH TRIGGER LOCKING MEANS Filed March 2, 196e Hg- E lNvENToR. HARVEY KoRsHAK ATTORNEY United States Patent O 3,379,852 PQWER OPERATED KNIFE SWITCH TRIGGER LOCKING MEANS Harvey Korshak, Skokie, Ill., assignor to Scovill Manufacturing Company, Waterbury, Conn., a corporation of Connecticut Filed Mar. 2, 1966, Ser. No. 531,163 5 Claims. (Cl. 200-157) ABSTRACT F THE DISCLOSURE Switch trigger locking means for a power operated knife or other tool provided with normally open switch contacts, comprising a switch actuating trigger having contact engaging means, and locking means mounted on the knife or tool housing in such position that an exposed part of the locking means is raised to or above the plane of the lowermost part of the housing when in trigger locking position and must be manually lowered to a plane below the trigger when it is desired to unlock the trigger and permit trigger operation and closing of the switch contacts. The locking means is a button headed pin slidable in directions transverse to the axis of the pin, the button being exposed externally of the housing. The housing includes a stop or abutment so positioned that the trigger must be moved slightly longitudinally of the trigger before the trigger can be depressed to move one of the switch contacts toward the other. Thus the trigger is protected against accidental actuation by the positive locking means which prevents longitudinal movement and depression of the trigger, and by the trigger mounting which prevents depression of the trigger until it has been moved slightly longitudinally out of engagement with the stop or abutment in the housing.

This invention relates to switch trigger locking means adapted for locking the switch trigger of a power operated knife or other appliance for the purpose of preventing actuation of the trigger and closing of the switch contacts.

Conventional power operated knives are provided with buttons or other actuating means to close switch contacts. When the actuating means is in the form of a depressible trigger or the like located on the lower surface of the knife housing, there is likelihood of accidental depression of the trigger when-the knife is placed on a table and also when the knife is positioned in a battery charging stand to make contact with the contacts in the stand.

The main object of this invention is to prevent accidental or unintended actuation of the switch trigger by positively functioning locking means which must be manually moved by the user to unlocked position before the switch trigger can be actuated and the switch contacts be closed.

Another object is to provide locking means which are automatically moved into locking'position when the knife is placed on a table or other support.

The locking -means is a button headed pin slidable in directions transverse to the axis of the pin, mounted in the knife or tool housing in such position that the button portion of the locking device is raised to or above the plane of the lowermost part of the housing when in trigger locking position, and must be manually lowered to a plane below the trigger when it is desired to unlock the trigger and permit trigger operation and closing of the switch contacts. Due to the location and construction of the trigger locking means, placement of the knife on a table or on a charging stand while the trigger is unlocked, automatically pushes the button headed pin Patented Apr. 23, 1968 ICC upwardly to the plane of the lowermost part of the knife and thereby prevents trigger actuation.

The trigger is mounted in a housing which includes a stop or abutment so positioned that the trigger must be moved slightly forwardly longitudinally of the trigger and housing before the trigger can be depressed to move one of the switch contacts toward the other contact. The pin portion of the locking device of my invention, when in raised locking position, abuts the forward end of the trigger and prevents movement of the trigger. Thus the switch trigger is doubly protected against accidental actuation, iirst, by the positive locking means which prevents forward movement of the trigger, and secondly, by the trigger mouting in the housing which prevents depression of the trigger until it has been moved slightly forwardly out of engagement with the stop or abutment in the housing.

The objects and advantages of the invention will be apparent from the drawings and following specification.

In the drawings:

FIG. 1 is an elevational side view, partly in section, of the forward end of a power operated knife, with the housing partly broken away to expose the switch contacts, trigger and locking means embodying this invention.

FIG. 2 is a view similar to FIG. 1, on an enlarged scale, of the contacts, trigger and locking means in locking position.

FIG. 3 is a view similar to FIG. 2 showing the locking means in unlocked position, the trigger having been moved forwardly and depressed, and contacts closed.

In the embodiment of the invention shown in the drawings, the forward end of a power operated knife housing is designated 10, and blades (broken away) at 11. The housing encloses a motor 12 and gearing 13 for reciprocating the blades. Switch contacts 14, 15, on leaf springs mounted at 16, are normally spaced apart as shown in FIG. l. The housing is provided with an opening in its lower wall through which a switch actuating trigger is accessible to the user of the knife.

The switch trigger 20 has a rearward generally horizontally disposed end 21, an upwardly extending contact actuating post 22, forward generally horizontally disposed end 23, and finger grip member 24. The rearward end 21 of the trigger normally rests on the ledge 25 of the housing adjacent the switch trigger receiving opening. The forward end 23 of the trigger normally extends over the slotted edge 26 of the housing adjacent the forward edge of the opening. The trigger 20 is urged into normal position by a pressure exerting spring 27 which bears at one end against the angle bracket 28 fixed in the housing, and at its other end against the post 22, being retained by a rod 29 provided with a downwardly bent end 30 retained between the post 22 and upward projection 31.

The horizontal portion of the bracket 28 also serves to confine the trigger end 23 by bearing on the upper surface of said end, and the rearward end 21 of the trigger abuts a stop shoulder 32 above the ledge 25, as shown in FIGS. 1 and 2. The stop 32 prevents upward movement of the trigger until the trigger has been moved slightly forwardly.

The housing 10 is formed to provide a depending casing 35 which extends transversely of the housing and is generally V-shaped in cross section longitudinally of the housing, providing a downwardly and rearwardly inclined wall 36. The casing 35 supports and houses the trigger locking means. The wall 36 is provided with a slot 37, the lower surface of which is aligned with the slotted edge 26 as best shown in FIG. 2.

A locking device consists of a pin 40 and head or button 41, mounted in the depending casing 35 by lock washer 42, with the Vpin 40 extending through the slot 37. The pin 40 is slidable in directions transverse to its axis. When the button 41 is in the raised position of FIGS. 1 and 2, the free end of the pin contacts the trigger end 23 and prevents forward movement of the trigger as a whole. When the button 41 has been manually depressed to slidably move the pin downwardly in the slot 37, the pin bears on the slotted edge 26 out of contact with the trigger end 23, thus permitting forward movement of the trigger by manual actuation.

In FIG. l, the knife housing 10 is shown as resting on the surface 43, with the lower-most parts of the ledge member 25 and lock casing 35 bearing on said surface. To be in trigger locking position, the button 41 of the locking pin 40 must be raised at least to the plane of the surface 43 so that the free end of the pin obstructs forward movement of the trigger 20 by contact with the trigger end 23. In this position, the rearward end of the trigger abuts the stop shoulder 32 in the housing and the forward end is confined by the bracket 28 as well as the pin 40. Therefore the trigger cannot be actuated to make the post 22 move the contact 15 into contact closing position. The user must manually depress the locking button 41 to slide the pin downwardly into the position of FIG. 3. Then the trigger can be manually actuated by pressure on the finger grip 24 to move the trigger forwardly slightly, freeing the rearward end 21 from the stop 32 and permitting upward movement of the trigger as a whole and of the post 22 into contact with the point 15 to close the switch contacts.

After pressure has been removed from the trigger 20, the spring 27 returns the trigger 20 from the FIG. 3 position to the normal position of FIGS. 1 and 2. Then the user may lock the trigger by moving the button 41 upwardly into trigger obstructing position. If the user fails to lock the trigger by moving the button upwardly into the position of FIGS. 1 and 2, the button will extend downwardly beyond the lowermost surface of the part 3S. If the knife is then placed on a surface 43 or into a battery charging stand (not shown), the placement of the knife automatically pushes the Abutton 41 upwardly and moves the pin into trigger obstructing position.

The locking device shown and described provides positively functioning means for locking the trigger into irnmovable position, and thus cooperates with the stop shoulder 32 to prevent contact closing motion of the trigger.

In describing the invention, reference has been made to a particular example embodying the same, but I wish it to be understood that the invention is not limited to the construction shown in the drawing and that various changes may be made in the construction and general arrangement of parts without departing from the invention. The claims define the locking means as applied t=o a power operated knife, but are intended to include other tools and appliances in which said means may be embodied without the exercise of inventive ingenuity. Also, the claims define the contact actuating member as a trigger but are intended to include triggers, buttons or other members which move the contacts into switch closing position. The normal position of the trigger, referred to in the claims, is the position in which the trigger is not engaging a switch contact and the contacts are in open position.

Iclaim:

1. A power operated knife having a housing and a pair of normally open switch contacts in the housing, comprising (a) a switch actuating trigger,

(b) means yieldably holding the trigger in normal position,

(c) contact engaging means 0n the trigger normally out of engagement with the contacts,

(d) an abutment in the housing bearing on the trigger and preventing depression of thta trigger relatively to the housing while the trigger is in normal position, and

(e) locking means mounted on the housing and movable into trigger obstructing position by contacting the trigger to prevent longitudinal movement of the trigger, and movable out of obstructing position to permit the trigger to be manually moved longitudinally out of engagement with the abutment and to be depressed and thereby move the contact engaging means into switch closing position, said locking means including a part accessible externally of the housing in such position that said part is raised to or above the plane of the lowermost part of the housing when in trigger locking position and must be manually lowered to a plane below the trigger when it is desired to unlock the trigger and permit trigger operation to close the switch contacts.

2. The power operated knife dened by claim 1, in which the contact engaging means on the trigger is a post which rises from the trigger between the trigger ends, and the means yieldingly holding the trigger in normal position is a pressure exerting spring which has one end bearing against said post and the other end bearing against a xed part of the housing, whereby the trigger is urged into abutment bearing position and cannot be moved longitudinally' of the trigger out of abutment bearing position until the locking means has been manually moved out of trigger obstructing position.

3. A power operated knife having a housing and a pair of normally open switch contacts in the housing, comprising (a) a switch actuating trigger,

(b) means yieldably holding the trigger in normal position,

(c) contact engaging means on the trigger normally out of engagement with the contacts,

(d) an abutment in the housing bearing on the trigger and preventing depression of the trigger relatively to the housing while the trigger is in normal position, and

(e) locking means mounted on the housing and movable into trigger obstructing position by contacting the trigger to prevent longitudinal movement of the trigger, and movable out of obstructing position to permit the trigger to be manually moved longitudinally out of engagement with the abutment and to be depressed and thereby move the contact engaging means into switch closing position, said locking means comprising a pin extending into the housing adjacent one end of the trigger, said pin being slidable in the housing in directions transverse to the pin, and a button on the pin accessible externally of the housing for slidably moving the pin into and out of trigger obstructing position.

4. A power operated knife having a housing `and a pair of normally open switch contacts in the housing, comprising (a) a switch actuating trigger,

(b) means yieldably holding the trigger in normal position,

(c) contact engaging means on the trigger normally out of engagement with the contacts,

(d) an abutment in the housing bearing on the trigger and preventing depression of the trigger relatively to the housing while the trigger is in normal position, and

(e) locking means mounted on the housing and movable into trigger obstructing position by contacting the trigger to prevent longitudinal movement of the trigger, and movable out of obstructing position to permit the trigger to be manually moved longitudinally out of engagement with the abutment and to be depressed and thereby move the contact engaging means into switch closing position, said housing having a depending casing portion on which the permit the trigger to be manually moved longitudinally out of engagement with the abutment and to be depressed and thereby move the contact engaging means into switch closing position, said abutment bearing on the rear end of the trigger, and the locking means when in locked position bearing against the forward end of the trigger, said trigger having a finger grip portion between said ends for moving the trigger longitudinally forwardly when the locking means is in unlocked position and freeing the rearward trigger end from the abutment to permit depression of the trigger into switch closing position.

5. A power operated knife having a housing and a pair of normally open switch contacts in the housing, 10 comprising (a) a switch actuating trigger,

(b) vmeans yieldably holding the trigger in normal position,

(c) contact engaging means on the trigger normally 15 out of engagement with the contacts,

References Cited UNITED STATES PATENTS (d) an abutment in the housing bearing on the trigger 1393509 10/1921 De Reamer 20a-IS7 and preventing depression of the trigger relatively 3308'535 3/1967 Freeman et al' 200`-157 to the housing while the trigger is in normal posi- FOREIGN PATENTS l10n and 20 619,571 4/1961 Italy.

(e) locking means mounted on the housing and movable into trigger obstructing position by contacting the trigger to prevent longitudinal movement 0f the trigger, and movable out of obstructing position to ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner. 

